[SOLVED] zoom to fit in QGraphicsView

loladiro

I think what you want to do is use a 100x100 scene, scale that to fit your graphics view with QGraphicsView::scale and then you can use the mapFromScene and mapToSence functions to get what you want. Does that help?

jk_mk

I have managed to fit my scene to QGraphicsView by using these:

@Canvas::Canvas(): QGraphicsScene(0,0,214,256)
{
}@

and
@ if (!pixmapItem) {

QPixmap tmpmap (QPixmap(fileName, 0, Qt::AutoColor));
    pixmapItem = scene->addPixmap ( tmpmap.scaled (214,256) );

        ui->graphicsView_inputImage->setScene(scene);
    } else {

QPixmap tmpmap (QPixmap(fileName, 0, Qt::AutoColor));
pixmapItem->setPixmap(tmpmap.scaled (214,256));
}@

But still I have the problem of the real coordinates. Now in x coordiantes I am taking these (0,214) and in y coordinates I am taking these (-100,100).Could you explain how to do the mapToScene? What I should write as a press mouse event instead of these?

@void MainWindow::mousejustpressed(int x,int y)
{
int k1=size_y-y;

unsigned char value;

QImage image(scene->sceneRect().size().toSize(), 
QImage::Format_RGB32);

QPainter painter(&image);
scene->render(&painter);

value=image.pixel(x,k1);

}@

loladiro

@Canvas::Canvas(): QGraphicsScene(0,0,100,100)
{
}
@

@QPixmap tmpmap (fileName, 0, Qt::AutoColor);
if (!pixmapItem) {
pixmapItem = scene->addPixmap (tmpmap);
ui->graphicsView_inputImage->setScene(scene);
ui->graphicsView_inputImage->scale(ui->graphicsView_inputImage->width()/scene->width(),
ui->graphicsView_inputImage ->height()/scene->height());
} else {
pixmapItem->setPixmap(tmpmap);
}@

@ void MainWindow::mousejustpressed(int x,int y)
{

 unsigned char value;

    QImage image(scene->sceneRect().size().toSize(),
    QImage::Format_RGB32);

    QPainter painter(&image);
    scene->render(&painter);

    value=image.pixel(ui->graphicsView_inputImage->mapToScene(x,y));
}

@

jk_mk

Thanks for your reply, now I am getting to the point.But when I run this code I get one error:

_ error C2664: 'QRgb QImage::pixel(const QPoint &) const' : cannot convert parameter 1 from 'QPointF' to 'const QPoint &'_

Do you know how it could be solved?

loladiro

Sorry I forgot the toPoint():
@
void MainWindow::mousejustpressed(int x,int y)
{

unsigned char value;

QImage image(scene->sceneRect().size().toSize(),
QImage::Format_RGB32);

QPainter painter(&image);
scene->render(&painter);

value=image.pixel(ui->graphicsView_inputImage->mapToScene(x,y).toPoint());

}@
Hope that helps!

jk_mk

Yes, this is it!

Thanks a lot for your help

loladiro

Glad I could help. And don't forget to add [Solved] to the title.

jk_mk

How do I add the [Solved]?

loladiro

Click on edit in the original post and then change the title.

goblincoding

Thanks for the question and the input. I definitely got something from this thread :)